As conveyance devices of this kind, there are known an electric car type in which the pair of left and right carriage units of the conveying carriage are individually installed with a traveling drive motor for driving traveling wheels of the carriage units as described in Patent Document 1, and a friction drive type in which either or both of the pair of left and right carriage units are moved and driven by motor-driven friction drive wheels arranged at regular intervals on the movement path side as described in Patent Document 2.